• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.25 no.1
• /
• pp.10-18
• /
• 2014

In this paper, we propose a new frequency reconfigurable dual-band antenna. By using an electronically compact eighth-mode substrate-integrated-waveguide(EMSIW) resonator, we have designed a compact antenna, which performs dual-band movement by additionally loading a complementary split ring resonator(CSRR) structure. The EMSIW and CSRR structures are designed to satisfy the bandwidths of 1.575 GHz(GPS) and 2.4 GHz(WLAN), respectively. We load the CSRR with a varactor diode to allow a narrow bandwidth and to enable the resonance frequency to continuously vary from 2.4 GHz to 2.5 GHz. Thus, we realize a channel selection function that is used in the WLAN standards. Irrespective of how a varactor diode moves, the EMSIW independently resonates so that the antenna maintains a fixed frequency of the GPS bandwidth even at different voltages. Consequently, as the DC bias voltage changes from 11.4 V to 30 V, the resonance frequency of the WLAN bandwidth continuously changes between 2.38 GHz and 2.5 GHz, when the DC bias voltage changes from 11.4 V to 30 V. We observe that the simulated and the measured S-parameter values and radiation patterns are in good agreement with each other.

• Tribology and Lubricants
• /
• v.35 no.1
• /
• pp.71-76
• /
• 2019

The differential planetary gear reducer as a main component of the concrete mixer driving mechanism requires a strong torque to mix concrete compounds. As this component is currently dependent on imports, it is necessary to develop it by conducting a study on vibration analysis and the resonance problem. The noise and vibration of a concrete mixer reducer increase owing to the transmission error of planetary gears, and the damage of components occurs owing to the problems in design and production. In this study, the tooth-passing frequency is calculated to evaluate the noise and vibration of a mixer reducer, and a fast Fourier transform (FFT) analysis is conducted through a vibration test using an acceleration sensor. The vibration of the reducer is measured at three points of input and output of the shaft and planetary gear housing with fixed and variable revolutions per minute. The operating conditions of gears and bearings are evaluated by performing the FFT analysis, and the resonance problem is verified. The results show that No. 1 pinion and ring gears revolve disproportionately. The amplitude values appear high, and the wear of tooth faces occur in tooth-passing frequencies and harmonic components of No. 1 and No. 2 pinion-ring gears. Therefore, we conclude that design changes in the reducer and a correction of tooth profiles are required.

• Journal of Ocean Engineering and Technology
• /
• v.29 no.2
• /
• pp.191-198
• /
• 2015

In this study, we proposed a new type of dual-buoy wave energy converter (WEC) exploiting multi-resonance and analyzed the experimental results from a model test in a 2-D wave flume. A dual-buoy WEC using multi-resonance has two advantages: high efficiency at the resonant frequencies and the potential to extend the frequency range available to extract wave power from the WEC. The suggested WEC was composed of an outer buoy and an inner buoy sliding vertically inside the outer buoy. As the power take-off device, a linear electric generator (LEG) consisting of permanent magnets and coils fixed at each buoy was adopted. Electricity was produced by the relative heave motion between the two buoys. To search for the optimal shape of a dual-buoy WEC, we conducted experiments on the heave motion of a two-body system in regular waves without an LEG installed. Model tests with six combinations of experimental models were conducted in order to find the motion characteristics of a dual-buoy WEC. It was found that model 2, which included a ring-shaped appendage to move the resonant frequency of the outer buoy toward a high value, showed a higher relative heave response amplitude operator (RAO) curve than model 1. In addition, the double-peak shape of the heave RAO curve shown for model 2 indicated the extension of the frequency range for extracting wave power in irregular waves.

• Korean Journal of Optics and Photonics
• /
• v.17 no.5
• /
• pp.475-479
• /
• 2006

An integrated photonic K-band microwave bandpass filter has been proposed and demonstrated by incorporating a polymeric ring resonator. Its transfer characteristics were adjusted by shilling the resonance wavelength of the ring resonator via the thermooptic effect. The achieved performance of the filter includes the center frequency of 20 GHz, the attenuation of ${\sim}15dB$, the bandwidth of 2 GHz, and the corresponding quality factor of 10. The microwave output power within the passband of the device was adjusted at the rate of about 6.7 dB/mW in the range of 27 dB. This kind of device with electrically controllable transfer characteristics can be applied to implement microwave switches and other devices.

• The Journal of Korean Institute of Information Technology
• /
• v.17 no.3
• /
• pp.43-50
• /
• 2019

In this paper, we propose a S-band oscillator with a reduced electrical size by applying a vertical split ring resonator(VSRR). The VSRR is a type of split ring resonator that operates as a resonator by the capacitance and inductance generated between the microstrip lines arranged on the top and bottom of the dielectric substrate and it has an advantage that the electrical size of the resonance circuit can be reduced as compared with the conventional ring resonator. In this paper, we design a VSRR operating over S-band and an oscillator using the VSRR as the resonant circuit. The proposed oscillator showed the output of 5.9dBm at 2.4HGz and showed the phase noise characteristics of -112.58dBc at 100KHz offset frequency and -117.85dBc at 1MHz offset.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.02a
• /
• pp.229-229
• /
• 2012

It is significant issue to control the unwanted transverse electric (TE) modes in the vacuum chamber for preventing the position reading noise from the beam position monitor (BPM) of storage ring. We introduce shunt structure to control the frequency distribution of TE resonance modes excited in the vacuum chambers of the Pohang Light Source II (PLS-II). The design of shunt structure is performed using the full three dimensional finite-difference time-domain (FDTD) simulation. It is verified that the sympton of the BPM noise is not oberved up to the beam current of 190 mA in the commmissioning of PLS-II.

• Proceedings of the KIEE Conference
• /
• 2007.11a
• /
• pp.96-97
• /
• 2007

A stator of ultrasonic motor of high torque with a new configuration is proposed. The stator designed newly is two sided vibrator consisting of toothed metal disk with piezoelectric ceramic ring bonded on both face of disk. which generates a flexural traveling wave along the circumference of disk. it produces a large vibrating force and amplitude because the vibrator is sandwiched by two piezoelectric ring. The finite element method was used to compute the vibration mode of the stator with a outer diameter of 48mm. A 6th vibration mode was chosen as operation mode with resonance frequency about 72kHz. According to the design, the prototype stator was fabricated and its performance was measured.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.14 no.11
• /
• pp.885-891
• /
• 2001

Ring/dot-type step-down piezoelectric transformer was manufactured by using Pb[(Mn$\sub$1/3/Sb$\sub$2/3)$\sub$0.05/Zr$\sub$0.475/Ti$\sub$0.475/]O$_3$ ceramics, which have excellent high-power piezoelectric properties. The characteristics of step-down piezoelectric transformer as a function of load resistance at output terminal was examined. Voltage gain was greatly dependent on drive frequency and load resistance, and showed maximum voltage gain at the resonance frequency. The output voltage was linearly increased as the input voltage increased. Voltage gain of the step-down piezoelectric transformer with respect to input voltage was very stable when the load resistance was in the range of 50-500 $\Omega$ .

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.44 no.12
• /
• pp.7-11
• /
• 2007

In this paper, we proposed the dual-mode stepped impedance ring resonator bandpass filter for MMIC (Microwave Monolithic Integrated Circuit) applications using the dielectric-supported air-gapped microstrip line (DAML). The ring resonator fabricated by surface micromachining technology. This filter consists of a DAML resonator layer and a CPW feed line. The DAML ring resonator is elevated with $10{\mu}m$ height from GaAs substrate surface. This bandpass filter is $1-{\lambda}g$ type stepped impedance ring resonator including dual-mode resonance. From the measurements, we obtained attenuation of over 15 dB and insertion loss of 2.65 dB at the center frequency of 97 GHz. Relative bandwidth is about 12 % at 97 GHz. Furthermore, the proposed bandpass filter is useful to integrate with conventional MMICs.

• Journal of Biosystems Engineering
• /
• v.27 no.4
• /
• pp.293-300
• /
• 2002

Surface crack detection is an important aspect in the quality control process of egg markets. The acoustic vibration of an egg could be used as a critical factor in evaluating the eggshell quality. The mode shape indicates the egg vibration behavior at different locations with respect to the input impulse and provides important information for the optimum sensor location to obtain the desired acoustic measurements. Theoretical analysis and experimental measurements were conducted to determine the acoustic vibration modes in eggs. The resonant fiequencies of the first and second resonance mode of intact eggs were found to be distributed between 2kHz and 7kHz range. The measured mode shapes of an egg were similar to theoretical shapes of homogeneous, elastic spheres. An elliptical deformation at the equator ring of the egg was observed. The frequency peak of this mode was dominantly present in the frequency spectrum of an intact egg impacted at its sharp position. The mode shapes related to the first resonant frequency of an egg shelved that the optimum location for the measuring sensor was the 180 degrees position. A optimum location for the egg support was found to be the 90 degrees position having the smallest vibration magnitude.